As a method for obtaining a molded article having a predetermined shape, using a thermoplastic resin, there are generally various molding methods including injection molding, blow molding, extrusion molding, press-molding, and the like.
Besides these general molding methods, for example, Patent Document 1 discloses a method in which a thermoplastic resin is irradiated with an electromagnetic wave having a wavelength range of 0.78 to 2 μm through molding dies when the molten thermoplastic resin is filled in a cavity in a molding die. According to the method, the thermoplastic resin is heated more strongly than the molding die formed of rubber, due to the differences in physical properties between the rubber forming the molding die and the thermoplastic resin.
In addition, for example, Patent Document 2 discloses that a particulate thermoplastic resin in a cavity in a rubber molding die is irradiated with an electromagnetic wave having a wavelength range of 0.78 to 2 μm to heat and melt this thermoplastic resin, and then a molten thermoplastic resin is additionally filled in a space left in the cavity.